The present invention relates to a sheet processing apparatus and an image reading apparatus, in particular it relates to an apparatus for performing a sheet bundle binding process.
Conventionally, an image forming apparatus such as a copier, a printer, a facsimile machine and other devices that combine them have a sheet processing apparatus that stacks a bundle of sheets discharged from the image forming apparatus and staples (binding process) the bundle.
Some of such apparatuses are provided with a stitching unit comprising a head to drive staples and an anvil to receive and bend the staples to bind a bundle of sheets substantially in a center area thereof.
An example of such a sheet processing apparatus, as disclosed in Japanese Patent Publication 07-157180, has a partial guide attached directly to a head and an anvil to guide a bundle to pass between them.
Nonetheless, in a conventional sheet processing apparatus, the guide is extended traversing a moving direction of a bundle when a bundle passes through a transport path between the head and the anvil. The guide also extends parallel to the bundle surface opposite to the head and anvil, i.e. a width direction of the bundle. In this case, it is not possible to guide and support the bundle completely across its width direction. Therefore, an edge of the bundle in the width direction tends to droop down or get caught on other internal parts upon transporting or stitching. As a result, an accurate positioning of the bundle is obstructed, causing undesirable stitching.
If a guide is attached substantially across an entire region in a width direction of the bundle, it is possible to guide and support the bundle throughout the entire width direction. But a leading edge of the bundle is easy to get caught in a gap between the head, the anvil and the guide, causing inaccurate positioning of the bundle and improper binding of the bundle.
An object of the present invention, in view of the problems of the current technology, is to provide a sheet processing apparatus and an image reading apparatus that securely transports and properly stitches a bundle.
Further objects and advantages of the invention will be apparent from the following description of the invention.
The present invention provides a sheet processing apparatus comprising a stitching unit having a head to drive staples into a bundle of sheets and an anvil to receive and bend the staples driven from the head. When the bundle is to be stitched, the stitching unit moves perpendicular to a direction that the bundle is transported. The sheet processing apparatus according to the present invention also comprises a guide member attached between the head and the anvil to guide the bundle to a stitching position, and a supplement sheet guide member disposed upstream side of the guide member in a transport direction of the bundle. The supplement sheet guide will not contact a leading edge of the bundle, and retracts so that the supplement sheet guide does not hinder movements of the stitching unit when the stitching unit moves.
The supplement guide member can have an inclined contact portion that touches the stitching unit. When the stitching unit moves, the stitching unit abuts the inclined contact portion, and the supplement guide unit retracts not to obstruct the movement of the stitching unit.
In another aspect of this invention, the stitching unit has a roller that contacts the inclined contact portion.
The supplement guide member may be disposed on an upstream in a transport direction of the bundle where the supplement guide does not interfere with the movement of the stitching unit upon retracting.
The supplement guide member may be attached to the stitching unit so that when the stitching unit moves to a predetermined position, the supplement guide member retracts to a position where the supplement guide member does not interfere with movements of the stitching unit.
The sheet feeding apparatus of the invention can include an aligning means to align in a direction traversing a transport direction of the bundle; a moving means to move the stitching unit in a direction traversing a transport direction of the bundle; and a control means to control the moving means to adjust the position of the supplement guide member.
One aspect of the present invention provides an image forming apparatus comprising an image forming unit and a sheet processing apparatus for stitching the bundle of sheets with images formed by the image forming apparatus. The sheet processing apparatus can be the one described in any of the aspects mentioned above.